Conventional stirring containers and stirring apparatuses are used for stirring solid, liquid or gaseous materials. Particles of liquid and gaseous materials have higher degrees of freedom, so they can get mixed with each other autonomously even without an external force and, moreover, adequate mixing can be achieved through convection even when stirring is carried out in a single direction. Therefore, it is easy to design stirring containers and stirring apparatuses that are used for stirring liquid or gaseous materials.
Compared to the stirring of liquid or gaseous materials, stirring a solid material is difficult because the solid material needs to move and be adequately mixed. Because solid material particles cannot move without being driven by an external force, usually only particles near the stirring paddles can be stirred by the stirring paddles during the stirring process. Therefore, solid material must be stirred for a relatively long time to accomplish adequate mixing. If stirring time needs to be shortened, the speed of the stirring paddles needs to be increased. With increased speed the pushing force applied to the particles by the stirring paddles and the pressure from other particles must be taken into consideration to avoid damage to the particles. For this reason, there is still a limitation on the stirring speed.
To shorten the stirring time, most conventional stirring containers or stirring apparatuses are designed to have a large accommodating space and large stirring paddles so that more particles can be stirred at the same time. However, the large accommodating space means that there is a large gap between the container and the stirring paddles, which makes it difficult to adequately stir the solid material because more particles dwell in the gap without being stirred. On the other hand, the large stirring paddles might cause the particles to move only in a single direction or even cause all the particles to be driven by the stirring paddles simultaneously, which would make the stirring ineffective instead.
Accordingly, a need exists in the art to provide a better solution for improved stirring.